Abstract : The Upper Ocean Circulation project was based on observations of circulation with drifters, bottom pressure gauges and current meters and the interpretation of these data on basis of conceptual and hydrodynamic models of the mixed layers, mesoscale and their interactions. The focus was in the north-eastern Pacific phenomena. The principal findings were: (1) models demonstrate that mesoscale eddy circulation is significantly changed by the nonlinear interaction of the wind and eddy vorticity.; (2) the eastern Pacific mesoscale is observed to be more important to the dynamics of the propagation of near inertial motions than is the beta effect; (3) a new data set of upper ocean circulation in the California Current was acquired with drifters and moorings. Wind driven motions, both barotropic and Ekman, account for significant part of the variance of circulation and sea level variability; (4) zonal shear on the scale of 1500km and amplitude of 12-15 cm/sec with respect to 1500m was measured in the subtropical Pacific. This phenomenon has yet no theoretical explanation; (5) an eddy resolving, biologically active general circulation model has been configured for the California Current system.